 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.texteditor.spelling;

 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.ISafeRunnable;
 import org.eclipse.core.runtime.SafeRunner;

 import org.eclipse.jface.preference.IPreferenceStore;

 import org.eclipse.jface.text.IDocument;
 import org.eclipse.jface.text.IRegion;
 import org.eclipse.jface.text.Region;

 import org.eclipse.ui.internal.texteditor.TextEditorPlugin;
 import org.eclipse.ui.internal.texteditor.spelling.SpellingEngineRegistry;

 /**
  * System wide spelling service.
  * <p>
  * This class is not intended to be subclassed by clients.
  * </p>
  *
  * @since 3.1
  */
 public class SpellingService {

     /**
      * A named preference that controls if spelling is enabled or disabled.
      * <p>
      * Value is of type <code>Boolean</code>.
      * </p>
      */
     public static final String PREFERENCE_SPELLING_ENABLED= "spellingEnabled"; //$NON-NLS-1$

     /**
      * A named preference that controls which spelling engine is used.
      * The value is the spelling engine's extension id.
      * <p>
      * Value is of type <code>String</code>.
      * </p>
      */
     public static final String PREFERENCE_SPELLING_ENGINE= "spellingEngine"; //$NON-NLS-1$

     /** Preferences */
     private IPreferenceStore fPreferences;

     /**
      * Initializes the spelling service with the given preferences.
      *
      * @param preferences the preferences
      * @see SpellingService#PREFERENCE_SPELLING_ENABLED
      * @see SpellingService#PREFERENCE_SPELLING_ENGINE
      */
     public SpellingService(IPreferenceStore preferences) {
         fPreferences= preferences;
     }

     /**
      * Checks the given document. Reports all found spelling problems to the
      * collector. The spelling engine is chosen based on the settings
      * from the given preferences.
      *
      * @param document the document to check
      * @param context the context
      * @param collector the problem collector
      * @param monitor the progress monitor, can be <code>null</code>
      */
     public void check(IDocument document, SpellingContext context, ISpellingProblemCollector collector, IProgressMonitor monitor) {
         check(document, new IRegion[] { new Region(0, document.getLength()) }, context, collector, monitor);
     }

     /**
      * Checks the given regions in the given document. Reports all found
      * spelling problems to the collector. The spelling engine is chosen
      * based on the settings from the given preferences.
      *
      * @param document the document to check
      * @param regions the regions to check
      * @param context the context
      * @param collector the problem collector
      * @param monitor the progress monitor, can be <code>null</code>
      */
     public void check(final IDocument document, final IRegion[] regions, final SpellingContext context, final ISpellingProblemCollector collector, final IProgressMonitor monitor) {
         try {
             collector.beginCollecting();
             if (fPreferences.getBoolean(PREFERENCE_SPELLING_ENABLED))
                 try {
                     final ISpellingEngine engine= createEngine(fPreferences);
                     if (engine != null) {
                         ISafeRunnable runnable= new ISafeRunnable() {
                             public void run() throws Exception {
                                 engine.check(document, regions, context, collector, monitor);
                             }
                             public void handleException(Throwable x) {
                             }
                         };
                         SafeRunner.run(runnable);
                     }
                 } catch (CoreException x) {
                     TextEditorPlugin.getDefault().getLog().log(x.getStatus());
                 }
         } finally {
             collector.endCollecting();
         }
     }

     /**
      * Returns all spelling engine descriptors from extensions to the
      * spelling engine extension point.
      *
      * @return all spelling engine descriptors
      */
     public SpellingEngineDescriptor[] getSpellingEngineDescriptors() {
         SpellingEngineRegistry registry= getSpellingEngineRegistry();
         if (registry == null)
             return new SpellingEngineDescriptor[0];
         return registry.getDescriptors();
     }

     /**
      * Returns the default spelling engine descriptor from extensions to
      * the spelling engine extension point.
      *
      * @return the default spelling engine descriptor or
      * <code>null</code> if none could be found
      */
     public SpellingEngineDescriptor getDefaultSpellingEngineDescriptor() {
         SpellingEngineRegistry registry= getSpellingEngineRegistry();
         if (registry == null)
             return null;
         return registry.getDefaultDescriptor();
     }

     /**
      * Returns the descriptor of the active spelling engine based on the
      * value of the <code>PREFERENCE_SPELLING_ENGINE</code> preference
      * in the given preferences.
      *
      * @param preferences the preferences
      * @return the descriptor of the active spelling engine or
      * <code>null</code> if none could be found
      * @see SpellingService#PREFERENCE_SPELLING_ENGINE
      */
     public SpellingEngineDescriptor getActiveSpellingEngineDescriptor(IPreferenceStore preferences) {
         SpellingEngineRegistry registry= getSpellingEngineRegistry();
         if (registry == null)
             return null;

         SpellingEngineDescriptor descriptor= null;
         if (preferences.contains(PREFERENCE_SPELLING_ENGINE))
             descriptor= registry.getDescriptor(preferences.getString(PREFERENCE_SPELLING_ENGINE));
         if (descriptor == null)
             descriptor= registry.getDefaultDescriptor();
         return descriptor;
     }

     /**
      * Creates a spelling engine based on the value of the
      * <code>PREFERENCE_SPELLING_ENGINE</code> preference in the given
      * preferences.
      *
      * @param preferences the preferences
      * @return the created spelling engine or <code>null</code> if none
      * could be created
      * @throws CoreException if the creation failed
      * @see SpellingService#PREFERENCE_SPELLING_ENGINE
      */
     private ISpellingEngine createEngine(IPreferenceStore preferences) throws CoreException {
         SpellingEngineDescriptor descriptor= getActiveSpellingEngineDescriptor(preferences);
         if (descriptor != null)
             return descriptor.createEngine();
         return null;
     }

     /**
      * Returns the spelling engine registry.
      *
      * @return the spelling engine registry or <code>null</code> if the plug-in has been shutdown
      */
     private SpellingEngineRegistry getSpellingEngineRegistry() {
         return TextEditorPlugin.getDefault().getSpellingEngineRegistry();
     }
 }

